Unity Shader Notes

Shader.md

_Time: This built-in variable return a variable of the float4 type, meaning that each component of this variable contians different values of time as it pertains to game time.

Unity - Manual: Built-in shader variables

Tags are used to add infomation about how the object is going to be rendered. Unity has provided us with some default render queues, each with a unique value that directs Unity when to draw the object to the screen.
This are built-in render queues:

Render queue	Desc	value
Background	This render queue is rendered first. It is used for skyboxes and so on.	1000
Geometry	This is the default render queue. This is used for most objects. Opaque geometry use this queue.	2000
AlphaTest	'Alpha-tested geometry uses this queue. It's different from the Geometry queue as it's more efficient to render alpha-tested objects after all the solid objects are drawn.	2450
Transparent	This render queue is rendered after Geometry and AlphaTest queues in back-to-front order. Anything alpha-blended (that is, shaders that don't write to the depth buffer) should go here, for example, glass and particle effects.	3000
Overlay	This render queue is meant for overlay effects. Anything rendered last should go here, for example, lens flares.	4000

#prama surface surf Lambert aplha:fade nolighting

• Lambert: Use Lambertian Reflectance lighting model
• nolighting: disable any lighting
• alpha:face: signal to Cg that this is a Transparent Shader

Holographic Effect:

float4 c = tex2D(_MainTex, IN.uv_MainTex) * _Color; 
o.Albedo = c.rgb; 
float border = 1 - (abs(dot(IN.viewDir, IN.worldNormal))); 
float alpha = (border * (1 - _DotProduct) + _DotProduct); 
// viewDir 是平面的 nomal direction
// dot: 0      border: 1     alpha:  向量正
//                           _DotProduct: 0.25      alpha: 1
//                           _DotProduct: 0.75      alpha: 1
// dot: 0.5    border: 0.5   alpha:
//                           _DotProduct: 0.25      alpha: 0.625
//                           _DotProduct: 0.75      alpha: 0.875
// dot: 1      border: 0     alpha:   向量平行
//                           _DotProduct: 0.25      alpha: 0.25
//                           _DotProduct: 0.75      alpha: 0.75
o.Alpha = c.a * alpha; 

Blending textures:

float4 aTexData = tex2D(_ATexture, IN.uv_ATexture); 
float4 bTexData = tex2D(_GTexture, IN.uv_BTexture); 
float4 blendData = tex2D(_BlendTex, IN.uv_BlendTex); 

float4 finalColor = lerp(aTexData, bTexData, blendData.g); 

sampler2D myTex;
float4          myTex_ST;  // 附带的一个变量

// ...

float2 tiling = myTex_ST.xy; // 放大缩小的倍数 
float2 offset = myTex_ST.zw;  // 位移

float4 o = tex2D(myTex, i.uv * tiling + offset)
return o

图片变灰：由于视觉感光对 R,G, B 的敏感度不一样，所以取不同的权重。

float4 grayScale(float4 v) {
    float g = v.r * 0.299 + v.g * 0.578 + v.b * 0.114;
    return float4(g, g, g, v.a);
}

if (w < 0) w = 0;
if (w > 1) w = 1;
// 等于
w = clamp(w, 0, 1);